Stencil sheet



. Patented Jan. 8, 1929.

v UNITED STATES PATENT OFFICE.

snm'mo rionrr, or mono, 'JArAN.

srnncrr. snan'r.

llo'nrawing.

atmospheric influences pn using or storing,

and gives a large number of clear and sharp copies.

In carrying out the invention a base of o en-texture, porous material of any suitablec aracter, such as yoshino paper is coated or impregnated with a coatmg material prepared by mixing together a solut1on of a phenolic resin in a suitable solvent, such asalcohol, with a solution of esters of polysaccharides, such as cellulose nitrate, cellulose acetate and mannan acetate, in a sultable solvent, such as acetone, .alcohol and amyl acetate.

The phenolic resin is a condensation prod:

not of phenols and formaline or other aldehydes in the presence of a small amount of alkalies or acids on application of heat, and which is soluble in alcohol.

In the present invention other artificial or natural resins,such as coumarone resin, ester gum, colophony and shellac, may be added to the coating material. And, if necessary,'a suitable proportion of a tempering agent such as 011s, fats, fatty acids and waxes, an coloring matters, such as a dye or a pigment, may be added to the above described coating material.

The yoshino paper may be coated or impregnated with the solution above described in any desired manner; or the composition may be added into the paper stuif in a mixing hollander.

The proportions of the ingredients of the composition may vary according to several pircumstances, an example bemg as fol-' ows:

- Theterm esters of polysapcharides is inv Application filed May 18,

1926. Serial No. l09,973.

tended to include not only one of. definite esters of' polysaccharides, but also a mixture of them.

The wax-coated stencil sheet which hither- ,to commonly used, has the great disadvantages of being liable to pass the ink through the cracks caused accidentally by the.usual handling, and particularly sensitive to the action of heat. Other kinds of improved flexible stencil sheets are obtained by employing certain protein substances, particularly gelatine. It is very troublesome to preliminarily moisten the sheet in order to adapt it for making the stencil by pressure. Moreover the iron parts ofthe writing machine are very lnjuriously'afiected by the moisture Yof the sheets.

According to the present invention the porous base is coated or impregnated with a material, not hitherto employed for this a purpose, including phenolic resin andesters of polysaccharides. The coated sheet, as above described, being soft and flexible re- 'mains throughout an extended period of time practically unchanged without the drawback of becoming sticky or friable. By the pressure of a hand stylus or the blow of the type of a writing machine without moistening the sheet the clear characters may be easily produced thereon.

What I claim is y 1. In a stencil sheet, the combination with a base of fibrous material, of an impregnating com osition comprising resin, estersof polysacc arides and a tempering agent.

2, In a stencil sheet, the combination with a base of fibrous material, of an impregnating composition comprising a henolic resin,

esters of polysaccharides an agent.

3. A stencil sheet composed of a base of fibrous material and an impregnating composition comprising a phenolic resin, cellulose nitrate, stearine and castor oil.

4. A stencil 'sheet as specified in claim 3,

a tempering in which the said composition comprises'the' said substances in the following proportion; Phenolic resin, 20% solution; 200

Cellulose nitrate, 5% solution 100 Stearina 10 Castor'oil 20 In testimony whereof I aflix my si attire.

Y SHINJIRO H. RII 

